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July 18 (Reuters) - Southwest Airlines Co joined U.S. rivals on Thursday in cancelling more flights until early November due to the continued grounding of Boeing Co's 737 MAX, which has also prompted the low-cost carrier to freeze new pilot hiring.

Dallas-based Southwest said on Thursday it would schedule without the 737 MAX until Nov. 2, a decision that proactively removes about 180 daily flights from its schedule, more than the 150 daily flights it was removing through early October.

Boeing's top-selling 737 MAX was grounded worldwide in March after two deadly crashes in Indonesia and Ethiopia that together killed 346 people. The timing of its return to service is uncertain.

With deliveries also on hold, Southwest has had to defer two new-hire pilot classes and two captain upgrade classes for existing pilots until it has more clarity, Southwest said in an e-mailed statement.

As of March 31, Southwest was expecting to take delivery of 34 additional MAX 8s and seven MAX 7s in 2019.

It received three MAX 8 jets before the March 13 grounding by the U.S. Federal Aviation Administration, which must approve updated software and training by Boeing meant to ensure that the plane is safe to fly again.

A Boeing official told Reuters last month that the company will not submit the updates until at least September following the discovery of a fresh flaw. U.S. airlines had previously expected the MAX to be flying again at some point this summer.

American Airlines Group Inc and United Airlines Holding also have removed the 737 MAX from their flying schedules until early November.

United Airlines, with 14 MAX jets, posted quarterly earnings on Tuesday that showed a boost in unit revenues thanks to reduced seat capacity in the sector, though costs are seen spiking over the year due to the grounding.

Southwest, the world's largest MAX operators with 34 jets, and American are due to report quarterly earnings on July 25. (Reporting by Tracy Rucinski and Ankit Ajmera; Editing by Bill Trott and Marguerita Choy)